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<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>2栏自适当布局</title>
  <style>
    * { margin: 0; padding: 0;}
    .content-main aside { float: left; width: 200px; background-color: moccasin; margin-right: 10px}
    .content-main article { overflow: hidden; }
  </style>
</head>
<body>
  <section class="main">
    <header>头部</header>
    <section class="content-main">
      <aside>
        <ul>
          <li>左侧目录</li>
        </ul>
      </aside>
      <article>
        <h1>文章内容</h1>
        <p>文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情</p>
        文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情文章详情
      </article>
    </section>
    <footer>底部</footer>
  </section>
  <!-- <style>
    .bfc-s-2 table {width: 200px;}
    .bfc-s-2 .bfc-content { width: 20000px; word-break: break-all;}
  </style>
  <section class="bfc-s-2">
    <table>
      <tr>
        <td>表头</td>
        <td>表头2</td>
      </tr>
      <tr>
        <td>单元格1</td>
        <td class="bfc-content">单元格2
            aassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadfaassdfadf
        </td>
      </tr>
    </table>
  </section> -->

  <!-- 两栏布局2 -->
  <style>
    .column2 {}
    .column2 aside{ float: right; width: 200px; height: 50px; background-color: #3fa;}
    .column2 main{ float: right; margin-left: -200px; width: 100%; height: 50px; text-align: center; background-color: #af3;}
  </style>
  <section class="column2">
    <main>This is main content</main>
    <aside>This is aside</aside>
  </section>
</body>
</html>